根据多个过滤器 JavaScript 从 JSON 数据计算平均值
javascriptweb developmentfront end technologyobject oriented programmingjson
假设，我们有一个像这样的对象数组 −
const arr = [
{ "SupplierName" : "John", "Category" : "A", "Points" : 3 },
{ "SupplierName" : "John", "Category" : "A", "Points" : 11 },
{ "SupplierName" : "John", "Category" : "A", "Points" : undefined },
{ "SupplierName" : "John", "Category" : "B", "Points" : 2 },
{ "SupplierName" : "John", "Category" : "B", "Points" : 6 },
{ "SupplierName" : "Praveen", "Category" : "A", "Points" : 3 },
{ "SupplierName" : "Praveen", "Category" : "A", "Points" : 7 }
];
我们需要编写一个 JavaScript 函数来接收一个这样的数组。
该函数应该执行以下操作 −
- 将重复的供应商分组为一个唯一的单独对象(重复是指具有相同 "SupplierName" 和 "Category" 字段的对象)。
- 将他们的分数加在一起
- 向每个对象添加一个新的 "average" 字段，其中包含该供应商的平均分数。
因此，最终输出应如下所示 −
const output = [
{ "SupplierName" : "John", "Category " : "A", "Points" : 14, "Average" : 7 },
{ "SupplierName" : "John", "Category " : "B", "Points" : 8, "Average" : 4 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 10, "Average" : 5 }
];
示例
const arr = [
{ "SupplierName" : "John", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "John", "Category " : "A", "Points" : 11 },
{ "SupplierName" : "John", "Category " : "A", "Points" : undefined },
{ "SupplierName" : "John", "Category " : "B", "Points" : 2 },
{ "SupplierName" : "John", "Category " : "B", "Points" : 6 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 3 },
{ "SupplierName" : "Praveen", "Category " : "A", "Points" : 7 }
];
const groupAndAverage = (arr = []) => {
const groups = arr.reduce((acc, obj) => {
const name = obj.SupplierName + obj.Category;
if (acc[name]) {
if (obj.Points) (acc[name].Points += obj.Points) && ++acc[name].Average;
}
else { acc[name] = obj;
acc[name].Average = 1;
// taking 'Average' attribute as an items counter(on the first phase)
};
return acc;
}, {});
// getting "average of Points" const res = Object.keys(groups).map( name => { groups[name].Average = Math.round(groups[name].Points/groups[name].Average);
return groups[name];
});
return res;
}; console.log(JSON.stringify(groupAndAverage(arr), undefined, 4));
输出
控制台中的输出将是 −
[
{
"SupplierName": "John",
"Category ": "A",
"Points": 22,
"Average": 6
},
{
"SupplierName": "Praveen",
"Category ": "A",
"Points": 10,
"Average": 5
}
]
